Electrically conductive coatings applied by internally charged electrostatic sprayers

ABSTRACT

The present invention provides compositions comprising a graphite, binder precursor and low polarity solvent that upon hardening form layers of an electrically conductive material. The compositions of the present invention are sprayable by an internally charged electrostatic sprayer.

This application claims the benefit of Provisional application Ser. No.60/129,154, filed Apr. 14, 1999.

FIELD OF THE INVENTION

The present invention relates to compositions sprayed by internallycharged electrostatic sprayers that harden to form conductive materials,and to articles comprising one or more layers of these conductivematerials.

BACKGROUND OF THE INVENTION

Automobiles are painted by various methods and some of them includeelectrostatic sprayers having high voltage (50 to 140 kilovolt)sprayheads. Automobile bodies used in such processes are usually made ofmetal and are electrically grounded to create a voltage differentialbetween the spray head and the automobile body. An electrode in thespray head charges droplets of paint, and a charged spray cloud from thespray head is attracted to the grounded automobile body. Paint transferefficiency (i.e., the amount of paint transferred from a sprayer to asubstrate surface) is increased as the paint to be sprayed becomescharged. Internally charged electrostatic sprayers typically have a tubeinside the spray head and are able to charge approximately 90% of thepaint within the tube. Externally charged electrostatic sprayerstypically have external projections surrounding the spray head orificeand charges paint leaving the spray head. Externally chargedelectrostatic sprayers charge a smaller percentage of paint than do theinternally charged sprayers and painting processes using externallycharged electrostatic sprayers typically provide lower paint transferefficiencies than processes using internally charged electrostaticsprayers.

Most automobile bodies also contain plastic parts, such as plasticexterior car body panels and plastic trim components. Duringelectrostatic spray painting, electrostatic charges accumulate onsurfaces of uncoated plastic parts and reduce the potential betweenspray heads and uncoated plastic surfaces. A reduced potentialdiminishes electrical forces acting on charged paint droplets.Accumulated surface charges may also result in an opposing electricalfield on uncoated plastic surfaces repelling air-borne paint particlesand resulting in low paint transfer efficiency when plastic surfaces areelectrostatically sprayed.

Plastic surfaces coated with conductive primers are thought to reduceaccumulation of surface charges during electrostatic spray painting.Coated plastic parts are attached to an automobile body prior topainting and can be grounded just like metal allowing the plastic to“look” like metal when subsequently electrostatically sprayed withtopcoat, clearcoat, and/or other automotive finishes. Unfortunately,internally charged electrostatic sprayers are unable to spraycompositions, which form conductive coatings with high efficiencybecause of track back. Track back refers to the ability of electricityto travel along the paint spray and return back to the electrostaticsprayer. Most paint compositions sprayed by an internally chargedelectrostatic sprayer are not conductive enough to result in track backwhen being sprayed. However, compositions which form conductivecoatings, sprayed with an internally charged electrostatic sprayer,provide a path for electricity to track back and short out the sprayer.Therefore, airsprayers, or externally charged electrostatic sprayer, areusually used to coat plastic parts before automobile manufacture. Thenthe coated plastic parts are attached to the automobile body and thenprimed a second time (simultaneously with the application of a primer tometal parts) prior to being painted. Consequently, the surfaces of theplastic parts typically include two layers of primer.

Compositions, which form conductive coatings and are sprayable by aninternally charged electrostatic sprayer onto both metal and plasticwould be desirable. Both metal and plastic parts could be primed at thesame time and the composition would eliminate a manufacturing step ofpre-coating plastic parts prior to automobile body assembly. Using aninternally charged electrostatic sprayer, to spray such a composition,would increase paint transfer efficiency compared to processes usingexternally charged electrostatic sprayers.

SUMMARY OF THE INVENTION

The present invention provides compositions comprising graphite, binderprecursor, and low polarity solvent The compositions are capable ofbeing sprayed by an electrostatic sprayer that is internally charged andthat upon hardening forms a layer of electrically conductive material.Both metal and plastic parts of an automobile body may beelectrostatically sprayed with compositions of the present invention sothat plastic parts are primed only once during manufacturing reducingthe costs of separately applying a layer of conductive material to aplastic part prior to automotive assembly. The compositions of thepresent invention may also be used as primers for metal parts that areapplied prior to the electrostatic spraying of topcoat. Consequently,the conductive compositions of the present invention provide, in part,at least two functions: a primer for metal and a conductive surface toplastic. The conductive compositions of the present invention arecapable of being sprayed through the spray head of an internally chargedelectrostatic sprayer without track back and shorting out the sprayequipment (firefault limit is typically set at 180 microamp). The sprayhead of an internally charged electrostatic sprayer used to spraycompositions of the present invention may have a voltage in the range ofabout 50 to about 140 kilovolts, preferably about 80 to about 90kilovolts. By electrostatically spraying compositions a step is removedfrom an automobile manufacturing process. Automobile manufacturers maytherefore obtain a cost savings. In addition the coatings of the presentinvention are chip resistant, impact resistant, have a good appearanceand have good adhesion to metal and plastic.

The present invention also provides an article comprising a substrateattached to a layer of electrically conductive material. Thecompositions of the present invention harden to form a coating (a layerof electrically conductive material) on the surface of a substrate.

The present invention also provides a process of coating comprising thesteps of spraying with an internally charged electrostatic sprayer acomposition comprising graphite, binder precursor, and a low polaritysolvent

As used herein, with respect to the present invention, the followingshall apply:

“capable of being sprayed electrostatically” refers to compositionssprayed by an internally charged electrostatic sprayer without resultingin track back.

“composition” refers to the flowable state of a coating comprisingbinder precursor, graphite and a low polarity solvent.

“coating” refers to a hardened composition described above.

“pigment” refers to carbon black, graphite, TiO₂ or other particles thatprovide color to a composition.

DETAILED DESCRIPTION OF THE INVENTION

Compositions of the present invention contain a binder precursorincluding one or more resins that harden to form a binder. A binderprecursor may include a hydroxy containing resin, such as polyester,acrylic modified alkyl, acrylic polyols, epoxy, isocyanate, acrylate,methacrylate or combinations thereof. Polyester resins are the preferredbinder precursor and include polyester urethane, polyester epoxy, orcombinations thereof. Preferably, a polyester used in the presentinvention has a hydroxyl number of about 100 to about 250, a numberaverage molecular weight of about 500 to about 9000, and an acid numberof 1 to about 40. A binder precursor of the present invention preferablycomprises about 45 to 85 weight percent of a hydroxyl containing resin.

A binder precursor of the present invention also includes one or morecross-linking resins, preferably melamine resin. A melamine resinsuitable for use in the practice of the present invention includes anon-alkylated melamine resin, a partially alkylated melamine resin, acompletely alkylated melamine resin, a melamine formaldehyde resin orcombinations thereof. Suitable partially alkylated melamine resin and/orfully alkylated melamine resin used in the practice of the presentinvention includes CYMEL 1133, RESIMENE 755, CYMEL 1168, RESIMENE 735,CYMEL 327, RESIMENE BM-5503 or combinations thereof. The melaminescommercially known as CYMEL are sold by Cytex, West Patterson, N.J. Themelamines commercially known as RESIMENE are sold by Solutia,Springfield, Mass. Other cross-linking resins suitable for the practiceof the present invention include isocyanates such as blocked and/orunblocked isocyanates such as DESMODUR BL-3175 sold by Bayer, Toronto,Ontario. A binder precursor preferably includes about 15 weight percentto about 55 weight percent of cross-linking resin.

Compositions of the present invention include one or more low polaritysolvents. Allow polarity solvent, as used herein, is defined as asolvent having a polarity in the range of 1 to 4.5 Hansen (H-bondingpolarity), preferably in the range of 1 to 3.0 Hansen (H-bondingpolarity). Preferred solvents include esters and aromatic hydrocarbonsolvents. Aromatic hydrocarbons used in the practice of the presentinvention include compounds having a six carbon ring structure such astoluene, ethyl-benzene or xylene. Preferred aromatic hydrocarbonsinclude those having a boiling point in the range of about 150° C. toabout 180° C. such as AROMATIC 100, SOLVESSO 100 sold by Exxon, Baytown,Tex. and SHELLSOL A sold by Shell Company, Houston, Tex. The mostpreferred aromatic hydrocarbons include those having boiling points inthe range of approximately 180° C. to 220° C. such as AROMATIC 150 soldby the Exxon Company, Baytown, Tex., SOLVESSO 100 sold by the ExxonCompany, Baytown, Tex., SHELLSOL AB sold by Shell Company, Houston, Tex.Other suitable aromatic hydrocarbons used in the practice of the presentinvention include those having boiling points in the range of about 215°C. to about 295° C. such as AROMATIC 200 sold by the Exxon Company,Baytown, Tex. PANSOL AN-8N sold by Amoco Company, Altanta, Ga. may alsobe use in the practice of the present invention. Esters suitable for thepractice of the present invention include n-butyl propionate, n-butylacetate, iso-butyl acetate, primary amyl acetate, 2-ethyl hexyl acetateor combinations thereof Solvent concentration will depend on desiredcomposition viscosity and the components used to make the composition,

Graphites suitable for use in the practice of the present invention maybe either natural or synthetic, preferably synthetic. Examples of suchgraphites include M440, M450, M490, M850 and M890 (sold by AsburyGraphite Mills, Inc., Asbury, N.J.). Graphites may have a mean particlesize of about 1 micron to about 15 micron, preferably in the range ofabout 3 micron to about 9 micron. Graphites having mean particle size of5 micron is most preferred. Electrostatically sprayable compositions ofthe present invention include graphite to binder ratio of about 10/100to 40/100, preferably between about 20/100 to about 30/100. Not to beheld to any particular theory, it is thought that the combination of lowpolarity solvent in combination with the described pigment binder ratiosare responsible for inhibiting track back during composition sprayingand for making a conductive coating.

Carbon black is preferably added to a composition of the presentinvention. Examples of carbon black suitable for the practice of thepresent invention include conductive grades such as CONDUCTEX 975 ULTRA(sold by Columbian Chemical Company, Atlanta, Ga.), Printex XE-2 (soldby Degussa, Frankfurt, Republic of Germany), BLACK PEARLS 2000 (sold byCabot Corporation, Boston, Mass.). Compositions of the present inventioninclude a carbon to binder ratio of about 0/100 to 4/100. Electrostaticsprayable compositions preferably have a carbon black to binder ratio inthe range of about 0/100 to 2.0/100, most preferably 0/100 to 1/100.

Dispersants may be added to compositions of the present invention, inpart, for purposes of dispersing graphite, carbon black and/or otherpigments. Suitable dispersants used in the practice of the presentinvention include titanate esters such as TYZOR TE (sold by the Du PontCompany, Wilmington, Del.), polymer dispersants such as AB polymerdispersants as described in U.S. Pat. No. 4,656,226, or DISPERBYK 161,162, 170 (sold by Byk-Chemie, Wallingford, Conn.), comb dispersants suchas SOLSPERSE 24000 (Zeneca, Wilmington, Del.), or combinations thereof.

Additives optionally added to compositions of the present inventioninclude surface tension modifiers, rheology control agents, antipoppingadditives polyacryate, aryl acrylate, modified polysiloxanes orcombinations thereof. Conductive coatings of the present invention arepreferably gray in color and the blackness of a coating may be alteredby the addition of TiO₂. Adding TiO₂ to conductive coatings lightenscoating color. Adding colored organic or inorganic pigments to theconductive coating may form different coating colors. Extender pigmentssuch as barium sulfate and/or talc may also be added to the compositionsof the present invention.

Compositions of the present invention preferably include a catalyst,preferably an acid catalyst. Acid catalyst that may be used in thepractice of the present invention include, in part, para-toluenesulfonic acid (NACURE 2500), phenyl acid phosphate (NACURE 4575),dodecylbenzene sulfonic acid (NACURE XP-221, dinonylnaphthalenedisulfonic acid, or combinations thereof. The NACURES are sold by KingIndustries, Norwalk, Conn.

Method of Making Coatings

Pigment dispersions are used to make coatings of the present invention.Graphite may be combined with binder precursor, solvent and optionaladditives such as a dispersant, then dispersed by sand grinding, ballmilling, attritor grinding, or by other devices known by one skilled inthe art. Alternatively, graphite may be dispersed directly into thepaint formula Carbon black is combined with binder precursor, solvent,and optional additives such as a dispersant and dispersed byconventional methods such as ball milling, attritor grinding, or mediamilling. Pigment dispersions are then mixed with remaining compositioningredients, such as resins, solvents, and additives, to form the finalcomposition.

The compositions of the present invention may be applied to a substrateby spraying, brushing, dipping, or other application techniques known byone skilled in the art. It is preferred that the conductive primers ofthe present invention are applied to a substrate by an internallycharged electrostatic sprayer that has a spray head having a voltage ofabout 50 to about 140 kilovolts, or about 50 to about 150 kilovolts,preferably 80 to about 90 kilovolts. An example of an electrostaticsprayer suitable for the practice of the present invention includesSAMES 605 BELL sold by Binks-Sames, Livonia, Mich.

Upon being applied to a substrate, compositions of the present inventionare hardened by an external energy source, preferably heat Coatedsubstrates may be heated to about 230° F. to 350° F., preferably fromabout 235° F. to 245° F. until the composition is substantiallyhardened. The bake time may last from 15 minutes to 60 minutes, and morepreferably from 25 minutes to 45 minutes. Baking temperatures anddurations are dependent upon the components of a composition and willvary from composition to composition. Other external energy sources usedto harden the compositions may include ultraviolet light, electron beam,infared radiation, or combinations thereof.

Compositions of the present invention are applied to substrates,including in part, metal such as aluminum, steel, coated metals(cathodic electrocoat), or combinations thereof to form an article.Alternatively, the substrate may be plastic such as polycarbonate,nylon, polybutylene terephthalate, polyesters, or combinations thereofThe substrates may also be combinations of both plastics and metals.Preferably, the substrate is an automotive plastic such asnylon/amorphous polyphenylene oxide alloy commercially available asNORYL GTX (sold by General Electric, Jamaica, N.Y.);polycarbonate/polybutylene terephthalate commercially available as XENOY(sold by General Electric, Jamaica, N.Y.); Polycarbonate/ABS (sold byDow Chemical Company, Freeport, Tex.); or amorphous nylon commerciallyavailable as BEXLOY (sold by Du Pont, Wilmington, Del.). Theseautomotive plastics are used to make automotive fenders, body panels,bumpers, interior parts, spoilers, bumpers and other parts.

Upon hardening, the compositions of the present invention preferablyform a layer of conductive material having conductivity in the range ofabout 100 Randsburg to about 115 Randsburg, preferably greater than 120Ransburg up to about 140 Ransburg. The layer of conductive material mayhave a thickness of about 15 micron to about 50 micron, preferably fromabout 20 micron to about 35 micron. Coatings of the present invention(conductive materials) may be used in various applications that requirea conductive surface, such as to enhance the transfer efficiency of asubsequent coating, such as paint, to a substrate surface (such asplastics). Preferably, the coatings are used as conductive primers andenhance paint transfer efficiency to the exterior of automobile partsduring electrostatic spraying. The automobile parts may be metal,plastic, or combinations thereof.

EXAMPLES

The examples below are carried out using standard techniques, which arewell known and routine to those skilled in the art, except whereotherwise described in detail. The examples are illustrative, but do notlimit the invention. Coatings of the present invention werepreferentially formed by making pigment dispersions and combining thosedispersions with other components. All percentages are part by weightunless indicated otherwise.

DEFINITIONS DUPONT R-706 TiO2, commercially available from Du Pont,Wilmington, DE SOLVESSO 150 Aromatic hydrocarbon TYZOR TETriethanolamine titanate ester available from Du Pont, Wilmington, DECYMEL 1133 Melamine, partially alkyld, commercially available fromCytec, city, state CYMEL 1168 Melamine, commercially available fromCytec, city, state RESIMENE 755 Melamine, commercially available fromSolutia, St. Louis, MO RESIMENE 735 Melamine, commercially availablefrom Solutia, St. Louis, MO CYMEL 327 Melamine, commercially availablefrom Cytex, West Patterson, NJ RESIMENE-5503 Melamine, commerciallyavailable from Cytex, West Patterson, NJ DISCON L-1984 Acrylicsurfactant, commercially available from King Industries, Norwalk, CTNACURE XP-221 Acid Catalyst, commercially available from Chem Central,Philadelphia, PA AMP-95 Chem Central, Philadelphia, PA

Polyester Resin 1

628.25 gm (gram) caprolactone and 264.55 gm 1,4-cyclohexanedimethanolwere combined in a reactor vessel followed by the addition of 0.122 gmdibutyl tin dilaurate and 1.078 gm xylene. The reactor vessel was heatedto 25° C. and the temperature was allowed to reach 140° C. The contentsof the reactor vessel were incubated for 4 hours at 140° C. and thencooled to 80°C.

Polyester Resin 2

21.23 gm deionized water and 191.06 gm neopentyl glycol were combined ina reactor vessel with an inert gas purge. The contents of the reactorvessel were heated to approximately 65° C. and the following ingredientswere added to the reactor vessel: 25.95 gm trimethylol propane, 145.42gm azelaic acid, and 177.91 gm dodecanedioic acid. 11.36 gm toluene wascharged to a water separator. The contents of the reactor vessel werethen covered with inert gas and heated to 120°C. Water was removed fromthe reactor vessel by heating the vessel at temperatures of about 120°C. to about 240° C. The vessel was heated at 240° C. until the contentsof the reactor vessel had an acid number of about 0 to 1.5 and aGardener viscosity of Z2-Z4. The contents of the vessel were cooled to120° C. by the addition of 19.05 gm toluene and 88.6 gm AROMATIC 100.Next 39.40 gm neopentyl glycol and 0.085 gm stannous octoate (FASCAT2003 catalyst obtained from ELF Ato Chem, N.A., Inc., Philadelphia, Pa.)was added to the vessel followed by the addition of 106.95 gm trimethylhexamethylene diisocyanate (Creanova, Inc., Somerset, N.J.) over a 30minute period. The contents of the reactor vessel was heated held at120-145° C. for 30 minutes followed by the addition 94.57 gm AROMATIC100. The contents of the reactor vessel were covered with an inert gasand then cooled to 70° C., followed by filtering.

Pigment Dispersion 1

Dispersion 1 was prepared by combining 26.72 weight percent of apolyester resin commercially available as MCWHORTER 57-5789 (sold byMcWhorter Technologies, Carpentersville, Ill.), 48.29 weight percentAROMATIC 150 and 24.99 weight percent conductive graphite. Thedispersion was mixed for 3 hours using high-speed dispersing (HSD)equipment, such as HOCKMEYER high blade (style G), sold by HockmeyerEquipment Corp., Harrison, N.J.

Pigment Dispersion 2

Pigment Dispersion 2 was prepared by combining and mixing 26.57 weightpercent of a polyester Resin (MCWHORTER 57-5789), 29.98 weight percentn-butyl propionate, 29.98 weight percent AROMATIC 150, 9.18 gm AB blockcopolymer (glycidyl methacrylate/butyl methacrylate/methyl methacrylatedescribed in U.S. Pat. No. 4,656,226), and 4.3 weight percent of carbonblack. The mixture was processed through a 2-liter Netsch LMZ media millcontaining 0.6-5 0.8 mm zirconia media. Tip speed=14 m/sec atflow-rate=14 sec/half-pint for 1 hour in a one tank recirculationprocess.

Pigment Dispersion 3

Pigment Dispersion 3 was prepared by combining 14 weight percent of apolyester resin (80% solids, trimethylol propane/neopentyl glycol/1.6hexanediol/isophthalic/orthophthalic anhydride/adipic acid/dodecanedioicacid; molecular weight 6,000-10,000, hydroxyl number 130-155 and acidnumber 2-10 as described in U.S. Pat. No. 4,442,269), 9 weight percentAROMATIC 150, 9 weight percent butyl, cellosolve and 68 weight percentTiO2 (DuPont R-706). The is dispersion was mixed for 60 minutes usingHSD equipment and then pass through a 8 gallon sandmill (0.8-1.0 mmzirconia media) at 8 pounds/hour.

Composition 1

Composition 1 is an example of a coating that when hardened isconductive but is not capable of being sprayed with an internallycharged electrostatic sprayer. Composition 1 was prepared by combining5.9 weight percent of MCWHORTER polyester resin, 7.7 weight percentPolyester Resin 2, 5.9 weight percent of Polyester resin 3. Thefollowing ingredients were combined with the resin mixture: 10.0 weightpercent RESIMENE 735 and 2.0 weight percent CYMEL 1168; 3.8 weightpercent n-butanol; 3.0 weight percent 2-ethyl hexanol and 0.6 weightpercent acrylic surfactant (10 weight percent DISLON L-1984 solution inAROMATIC 100). The reaction mixture was allowed to mix for about 30minutes. Then 1.2 weight percent of a blocked acid catalyst (a solutionof 48.3 weight percent NACURE XP-221 sulfonic acid and 10.8 weightpercent AMP-95) was slowly added to the reaction mixture while stirringand the reaction mixture was mixed for an additional 30 minutes. Whilestirring, the reaction mixture was combined with 23 weight percentPigment Dispersion 3, 22.7 weight percent Pigment Dispersion 2 and 14.0weight percent Pigment Dispersion 1. The reaction mixture was mixed foran additional 30 minutes.

Composition 2

Composition 2 is an example of a composition that can be sprayed by aninternally charged electrostatic sprayer. Composition 2 was prepared bycombining 4.3 weight percent MCWHORTER polyester resin, 7.2 weightpercent Polyester Resin 2, and 5.5 weight percent of Polyester Resin 3.The following ingredients were combined with the resin mixture: 9.4weight percent RESIMENE 735, 1.8 weight percent CYMEL 1168, 3.8 weightpercent of alcohol n-butanol, 3.0 weight percent 2-ethyl hexanol, and0.6 weight percent of acrylic surfactant (10 weight percent DISLONL-1984 solution in AROMATIC 100). The reaction mixture was allowed tomix for about 30 minutes. 1.1 weight percent of an acid catalyst (asolution of 48.3% NACURE XP-221 sulfonic acid and 10.8% AMP-95 inisobutyl alcohol) was slowly added to the reaction mixture whilestirring and the reaction mixture was mixed for an additional 30minutes. While stirring, the reaction mixture was combined with 21.5weight percent Pigment Dispersion 3, 5.1 weight percent PigmentDispersion 2 and 36.6 weight percent Pigment Dispersion 1. The reactionmixture was mixed for an additional 30 minutes.

Test Procedures

The following test procedures were performed on coatings prepared formCompositions 1 and 2. Compositions 1 and 2 were sprayed to a filmthickness of about 25 microns on to a plastic substrate and baked for 25minutes at a substrate temperature of 115.56° C. The coatings arenumbered to correspond to the composition as illustrated in Table 1. Thedry conductivity of the coatings was measured using the RansburgSprayability Meter (Model 8333-00) sold by Ransburg Corporation,Indianapolis, Ind. Wet Resitivity was measured using the Sames AF200Resistivoltmeter (sold by Binks-Sames, Livonia, Mich.). The measurementswere taken using the equipment operating instructions from the supplier.

TABLE 1 Performance* Test Method Coating 1 Coating 2 Dry ConductivityRaysburg Sprayability 140 125 Wet Resistivity Same AP200 <5 16 μohm/cm²Resistability μohm/cm² Adhesion ASTM D-3359-93 100% pass 100% passHumidity Adhesion 100% pass 100% pass

The above tests demonstrate both coatings perform well having goodadhesion and conductivity. Coating 2 had a higher wet resistivity thanCoating 1 indicating Coating 2 has a lower conductivity in the wetstate.

Electrostatic Sprayability Test

The electrostatic spray test was performed by spraying Compositions 1and 2 with a Sames 605 Bell internally charged electrostatic sprayer(sold by Binks-Sames, Livonia, Mich.). The electrostatic sprayer was setat 80 kV (180 microamp) and sprayed for a duration described in Table 2.

TABLE 2 Composition Result Composition 1 Back Track occurred immediatelyafter the sprayer was turned on. The sprayer shorted out. Composition 2Back Track did not occur after 30 min nor at 99% Relative humidity andat 35° C.

Transfer Efficiency Test

Paint was sprayed as described above and the build up of a layer ofconductive material on a metal surface was measured using a FischerScope (sold by Fischer Company). The method used for quantifying theconductive material on the surface of the metal substrate was describedin equipment operating instructions from the supplier and are well knownin the art Transfer efficiency was determined by comparing the amountsprayed to the amount of conductive materials on the surface of themetal substrate.

TABLE 3 Voltage Composition 1 Composition 2 40 kV 15-20% 80 kV Notsprayable 60+%

Transfer Efficiency Test demonstrated Composition 2, a samplecomposition of the present invention, can achieve a higher painttransfer efficiency than Composition 1 because it can be sprayed athigher voltages. A painting process using an internally chargedelectrostatic sprayer and Composition 2 had a paint transfer efficiencythat was at least 2 fold greater than the same process using Composition1.

What is claimed is:
 1. A conductive primer composition comprisinggraphite, conductive carbon black, binder precursor and low polaritysolvent, wherein the composition contains graphite in a graphite tobinder weight ratio of about 10/100 to about 40/100 and the carbon blackin a carbon black to binder weight ratio of 0/100 to about 4/100, and iscapable of being sprayed by an internally charge electrostatic sprayerand of hardening to form a layer of an electrically conductive materialhaving a conductivity in the range of about 100 up to about 140 Ransburgunits.
 2. The composition of claim 1, wherein the internally chargedelectrostatic sprayer sprays the composition at a voltage of about 50 toabout 150 kilovolts.
 3. The composition of claim 1, wherein theinternally charged electrostatic sprayer sprays the composition at avoltage of about 80 to about 90 kilovolts.
 4. The composition of claim1, wherein the binder precursor comprises a hydroxyl containing resinand a crosslinking resin.
 5. The composition of claim 1, wherein thehydroxyl containing resin is selected from the group consisting ofpolyester, epoxy, acrylate, methacrylate, isocyanate, acrylic polyol andcombinations thereof.
 6. The composition of claim 4, wherein thecrosslinking resin is melamine.
 7. The composition of claim 1, whereinthe low polarity solvent is selected from the group consisting oftoluene, ethyl, benzene, xylene, n-butyl propionate, n-butyl acetate,iso-butyl acetate, primary amyl acetate, 2-ethyl hexyl acetate andcombinations thereof.
 8. The composition of claim 1, wherein thegraphite has a mean particle size in the range of about 3 micron toabout 12 micron.
 9. The composition of claim 1, wherein the binderprecursor comprises about 45 weight percent to about 85 weight percentof a hydroxyl, containing resin.
 10. The composition of claim 4, whereinthe binder precursor comprises about 15 weight percent to about 55weight percent of a cross-linking resin.
 11. The composition of claim 1comprising titanium dioxide.
 12. The composition of claim 1 comprisingcarbon black.
 13. The composition of claim 12 wherein the compositioncomprises carbon black in a carbon black to binder weight ratio of up toabout 2.0/100.
 14. The composition of claim 1 comprising a dispersant.15. The composition of claim 14 wherein the dispersant is selected fromthe group consisting of titanate ester, polymer dispersant andcombinations thereof.
 16. An article comprising a substrate attached toa layer of electrically conductive material, the electrically conductivematerial comprising a hardened composition of claim
 1. 17. The articleof claim 16 wherein the layer of electrically conductive material has athickness in the range of about 15 micron to about 50 micron.
 18. Thearticle of claim 16 wherein the substrate is plastic, metal orcombinations thereof.
 19. The article of claim 16 wherein the layer ofelectrically conductive material comprises titanium dioxide.
 20. Thearticle of claim 16 wherein the layer of electrically conductivematerial comprises carbon black.
 21. A process of coating comprising thesteps of: spraying with an internally charged electrostatic sprayer acomposition of claim
 1. 22. The process of claim 21 wherein theinternally charged electrostatic sprayer sprays the composition at about80 to about 90 kilovolts.
 23. The process of claim 21 wherein theinternally charged electrostatic sprayer sprays the composition at about50 to about 140 kilovolts.
 24. The process of claim 21 comprising thestep of spraying the composition onto a substrate surface.
 25. Theprocess of claim 24 wherein the substrate is the exterior of anautomobile.
 26. The process of claim 24 comprising the step of hardeningthe coating to form a layer of electrically conductive material.
 27. Acomposition comprising graphite, optionally conductive carbon black,polyester resin, melamine resin and low polarity solvent, capable ofbeing sprayed by an internally charge electrostatic sprayer and ofhardening to form a layer of an electrically conductive material.